Field of the Invention
The present invention relates to an electrode pattern of a touch panel and a forming method for the electrode pattern. More particularly, it relates to an electrode pattern of a touch panel and a forming method of the electrode pattern of a touch panel in which a bridge electrode for connecting the electrode patterns is formed.
Description of the Related Art
Generally, in a personal digital assistant (PDA), a notebook computer, an office automatic device, a medical instrument, or a car navigation system and the like a touch panel has been used for providing input means (pointing device) with the displays of the above-mentioned devices. A capacitive type has been used as a typical touch panel, in addition to a resistance film type, an electromagnetic induction type, and an optical type and the like.
Here, the capacitive type is classified as an analog way and a digital way. The pattern of a conductive for a sensor formed as a sheet shape is not necessary within a sensing region in the analogy way. On the contrary the patter of a conductive for a sensor is necessary within a sensing region. In the digital way, a capacitive touch panel may adopt the capacitance variation induced between human body's electrostatics and a transparent conductive for inducing based current to confirm a touch position. For detecting the position touched to the touch panel by a finger or stylus, various capacitive touch panel technologies have been developed.
In U.S. Pat. No. 6,970,160, a lattice touch-sensing system for detecting the touch position on a touch-sensitive surface has been disclosed as one example of the capacitive panel. The lattice touch-sensing system includes two capacitive sensing layers separated through dielectric materials, and each capacitive sensing layer is made of conducting elements arranged in a parallel wherein the conducting elements in the two sensing layers are arranged perpendicularly. In addition, the conducting elements each may be made of a series of patches in a diamond shape connected to each other through narrow conductive rectangular strips. The respective conducting element in a given sensing layer is electrically connected to a lead line of the lead line set, corresponding to one end or both ends thereof. Additionally, a control circuit may be included for providing an exciting signal to both sets of the conducting elements through the corresponding lead line set, receiving a sensing signal produced from the sensor elements when a surface is touched, and determining the touched position, based on the position of the affected bars in the respective layer.
The capacitive type may include two capacitive sensing layers which are formed in a space to each other by using dielectric material for inducing capacitive effect between the two layers. This configuration causes the touch panel to be very thick and thus is counter-thinned thereof. Furthermore, a conventional capacitive touch panel includes a substrate on both surfaces thereof on which two capacitive sensing layers are formed. In this point, a through hole is formed on the substrate to serve as a bias and further a circuit layering is adopted for connecting properly the conductor elements on the sensing layers, which causes the manufacturing of the capacitive panel to be difficult and complicated.
Accordingly, in order to solve the above-mentioned drawbacks, a technology for reducing the two capacitive sensing layers to one layer has been proposed.
FIG. 1 is a view illustrating an electrode pattern of a touch panel according to a prior art, and FIG. 2 is a cross-sectional view illustrating an electrode pattern of a touch panel according to a prior art. Hereinafter, a conventional touch panel and an electrode pattern according to a prior art will be described, referring to FIGS. 1 and 2.
As shown in FIGS. 1 and 2 (a), a first axis Rx electrode pattern 120 is formed on a substrate 110 and a second axis Tx electrode transparent pattern cell 131 are formed wherein the electrode patterns are shown in a section thereof in FIG. 2.
At this time, the first axis electrode pattern 120 and the second axis electrode transparent pattern 131 may be formed by using etching, sputtering, or screen printing and further the transparent pattern may be made of Indium-Tin Oxide (ITO).
After that, as shown in FIG. 2(b), a photo resist layer 10 is formed on the second electrode pattern cell 131 and then a dielectric material application layer 40 is formed by applying the dielectric material.
In subsequent, a dielectric layer 50 is formed by removing the photo resist layer 10, as shown in FIG. 2(c). Here, a bridge electrode 90 is formed on the dielectric layer 50 to connect electrically the second axis Tx electrode pattern cells 131 which are spaced.
However, since the bridge electrode of the electrode pattern of a conventional touch panel for connecting the electrode pattern cells 131 is exposed visibly, and thus a width of the bridge electrode is 10 μm and as a result metal is used for the bridge electrode in consideration of electric conductivity. However, the bridge electrode is exposed visibly due to different reflection rate and colors between the metal and surrounding LCD.
Further, in case where transparent ITO electrode in order to solve the visible exposure, a design of decreasing a conductive width is impossible due to a limitation of the electric conductivity for the transparent electrode and further an additional process for etching selectively the ITO and the metal is necessary.